An exhaust gas purification apparatus of a diesel engine (an internal combustion engine) having a turbocharger, is described in the PTL 1 (hereinafter, this apparatus will be referred to as—conventional apparatus—). The conventional apparatus has a diesel particulate filter (DPF). This filter has a honeycomb configuration including a number of passages, each defined by porous walls. When an exhaust gas flows through the passages or pores of the porous walls of the DPF, particulates included in the exhaust gas are trapped on surfaces of the porous walls and surfaces defining the pores of the porous walls.
In the diesel engine described in the PTL 1, immediately after the exhaust gas flows out from turbine blades (a turbine wheel) of the turbocharger, the exhaust gas flows under a turbulent condition. In the conventional apparatus, the DPF is disposed just downstream of the turbine blades. Thereby, the exhaust gas flows evenly into the DPF and thus, the DPF can efficiently trap the particulates included in the exhaust gas.